How do I save email attachments to OneDrive so that it removes it from my mailbox storage but the link stays in the email?

Hello @Ria Alison

I understand what you mean, but Outlook does not work in a way that reduces mailbox storage when you choose “Upload to OneDrive.” Here is how it actually behaves when you do that:

When you select Upload to OneDrive, Outlook only copies the attachment to OneDrive and inserts a sharing link into your email. It does not remove the original attachment from your mailbox. Because the attachment stays inside the message, your mailbox size will not decrease.

This is the expected design. The feature is intended for "easy sharing", not for "reducing mailbox usage".

*And the question is: Why does Outlook keep the attachment in both places, and what would happen if it didn’t?

Outlook intentionally retains the attachment in both your mailbox and OneDrive because this approach best supports data integrity, compliance requirements, and a consistent user experience. The “Upload to OneDrive” function is designed specifically for streamlined sharing, not for mailbox size reduction.

If Outlook were to automatically remove the attachment after uploading it to OneDrive, several risks and operational issues could arise:

• Compliance and preservation: Many organizations require that emails remain unchanged for legal, auditing, or retention policies. Removing attachments would alter the original message and could violate these obligations.
• Data loss risk: If the OneDrive file were later deleted, moved, or access permissions changed, the attachment would no longer be recoverable if it had already been removed from the mailbox.
• Offline availability: Users who access Outlook in offline mode, or on clients that do not fully support cloud attachments, would lose access to the file.
• User clarity: Automatically modifying emails without user action could lead to confusion or the perception that content has gone missing.

By maintaining the attachment in the email, Outlook ensures message integrity, data protection, offline accessibility, and predictable behavior across clients.

However, you can prefer these article to reduce your mailbox storage:

Storage limits in Outlook.com - Microsoft Support

For your reference:

Microsoft storage quotas - Microsoft Support

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